Modern buildings are often constructed from "tilt-up" concrete walls which are cast at the work site or factory precast, and masonary walls. The walls in such buildings are unitially attached to each other at the top using roof beams, on which the roof purlins and other roof components are supported.
In the past such buildings were constructed using wind and/or bond beams across the roof beams adjacent to the walls at each end to reinforce the top of the walls against the lateral force of wind. Further, in geographical locations where seismic forces are encountered, the lateral seismic effect has to be taken into account in determining the size of such reinforcing beams. In addition, such beams are also used to anchor the wall to the roof structure, reinforcing the wall against the vertical load of the roof structure. Plywood panels may also be used to form a roof sub-diaphragm in combination with such structures to reinforce the roof from lateral forces to prevent twisting and buckling. However, because of the material costs and the lack of sidewall columns in some situations, the use of wind and/or bond beams is not always satisfactory.
Because the roof support beams and other roof structures are often constructed from steel or other metal materials having a different thermal coefficient of expansion from that of the concrete or masonary walls to which the roof is attached, the force exerted during thermal expansion or contraction at the points of attachment between the roof structure and the walls may adversely affect the structural integrity of the building, and, thus, also has to be taken into account and makes the attachment of such wind and/or bond beams problematical.
Thus, the need exists for a support system capable of attaching the roof to the walls of a building, reinforcing the walls against the lateral loads of wind and seismic forces and the vertical load of the roof structure, reinforcing the roof by acting as a diaphragm to prevent twisting and buckling when lateral forces act on the walls, and permitting thermal expansion and contraction of the heterogeneous wall and roof components without adversely affecting the integrity of the assembled building.
The present invention solves these problems by providing a truss which extends along each end of the building, which is attached to the wall, roof and roof beams, and which provides lower material costs, reinforcement of both walls and roof against vertical and horizontal loads even in situations where there is a lack of sidewall columns, and a means for allowing normal thermal expansion and contraction of the attached heterogeneous components.